Final answer:
Edwin Hubble's research confirmed that galaxies beyond the Milky Way exist, providing a critical step in understanding the universe's structure. He also contributed foundational observations that would eventually support the contemporary concept of dark matter.
Step-by-step explanation:
Edwin Hubble's discovery confirmed the belief that galaxies exist beyond the Milky Way. Hubble's work overturned the then-prevailing view that the Milky Way was the entirety of the universe. Instead, he showed that spiral nebulae were indeed separate galaxies, much like our own. This revelation was a groundbreaking step in understanding the universe's vastness.
Hubble's observations of galaxies also led to the understanding that the number of galaxies is roughly the same in each area of the sky, and their density is about the same at all distances from us. This uniform distribution was important evidence for the models of the universe that were developed later. Additionally, Hubble's work laid the foundation for the discovery of dark matter, although that concept was not fully developed until later studies by other astronomers, such as Fritz Zwicky and Vera Rubin.